Percussion tool for wave-transmission apparatus



March 10, 1931. w. R. DEGENHARDT ET AL 1,796,089

PERCUSSLON TOOL FOR WAVE TRANSMISSION APPARATUS Original Filed Feb. 28, 1928 I I LL I L i\\\ s 2 A [32 Y clearly understood and Patented Mar. 10, 1931 UNITED STATES PATENT OFFICE WILLIAM RUSSELL D'EGENHARDT, OF LONDON, ALLAN FRED DE FRAINE, OF WEM- BLEY, AND ROBERT HENRY BICKNELL, DECEASED, LATE OF WESTMINSTER, ENG- LAND, BY ROBERT ALAN VIIMBERLEY BIGKNEELL, OF LONDON, ENGLAND, AND

ARTHUR BICKNELL, OF BIRMINGHAM ENGLAND, LEGAL REPRESENTATIVES OE ROBERT HENRY BICKNELL, DECEASED, ASSIGNORS TO THE FRANCOIS CEMENTA- TION GOIYIPANY, LIMITED, OF DONCASTER, ENGLAND, A BRITISH COMPANY PERCUSSION TOOL FOR HAVE-TRANSMISSION APPARATUS Original application filed February 28, 1928, Serial No. 257,768, and in Great Britain March 25, 1927.

Divided and this application filed June 10, 1929.

This invention relates to percussion tools for operation by compressional liquid wavetransmission mechanism. In the spring suspension of tools of this kind it is necessary to obtain resonance between the reciprocating mass and the resilient element. As is well known, in any spring suspension of a mass, if any predetermined natural period of oscillation is to be obtained, the resiliency or capacity of the spring suspension must bear a definite relation to the reciprocating mass which is supported and the greater the mass the more rigid must be the resilient support. For substantial masses and high periodicity of oscillation the yield of the spring suspension for a given force must be small and the compressibility of a volume of liquid is sufficient, in the case of a considerable reciprocating mass, to bring the natural period of the suspension suficiently low to correspond to the periodicity of the wave transmission, so that resonance is established for this periodicity. The use of liquid as a resilient body in a percussion tool of the above type has already been proposed either in the form of a single body or column of liquid or two bodies or columns on opposite sides of a dividing wall belonging to the body of the tool, the percussion or striking device or rod extending through the said liquid.

According to the present invention the per cussion rod is formed with a rearward extension or portion which passes through the working chamber and which is made of smaller diameter than the portion of the rod in front of the said rearward portion so as to provide a shoulder or area upon which the operating liquid in the said working chamber operates. The said rearward portion of the rod passes through a gland to the atmosphere.

In order that the said invention may be readily carried into effect, the same will now be more fully described with reference to the accompanying drawing which is an axial section showing a form of percussion tool constructed accord ing to this invention.

A. is the body or casing of the 5 B i Serial No. 369,834.

the percussion rod which is arranged centrally within the body A and passes through glands A A at the rear and forward ends of the tool body, C is the working chamber to which the operating wave-transmission liquid is admitted by means of a pipe C and D is the aforesaid chamber containing a single body of liquid (herein termed the liquid spring chamber) situated in the forward part of the tool body in front of the working chamber C.

The middle portion B of the rod B is situated in a bushing E and is made of larger diameter than the rear portion of the rod to provide an area for the operating liquid in the working chamber C to act upon; the required area for the liquid in the chamber D to act upon in order to move the rod rearwards is provided by making the front por-- tion of the rod, which is situated in a bush ing A of smaller diameter than the middle portion as shown. A collar B is provided for limiting the rearward movements of the rod B, and the forward movements are limited by the shoulder between the larger diameter portion and the smaller diameter front portion of the rod, the said collar and shoulder coming against the bushings E and A respectively.

As the middle portion B of the rod must be free to slide readily in the bushing E and there are during each oscillation considerable differences of pressure lDQi'A een the liquid spring chamber D and the working chamber C receiving the operating wave-transmission liquid, leakage is liable to occur from the working chamber into the liquid spring chamber and to prevent an undesirable accumulation of pressure in the latter chamber we mayprovide as shown a relief valve F which opens at a predetermined pressure. The said relief valve F would be set to open at about the mean pressure in the working chamber C. This relief valve forms the subject of our British Patent No. 293088 and may be replaced by any of the equivalent devices mentioned in the specification of that patent. The pipe C may be provided, as shown, with a spring controlled relief valve C similar to the relief valve F, A SOreWrdOWn valve G may also be provided for controlling the flow of liquid froin' the working chamber C to the liquid spring chamber D through a passage A in the tool body. This valve is opened when the-tooLis to be started working so as toen-r able the chamber 1) to be filled with liquid and is closed duringinormal working; it can,

however, be partly opened to any desired to vary the force extent during working so as oi the blow of the percussion rod B.

What we claimand desire to secure by Letters Patent of the United States is 1. In a percussion tool for operationby compressional liquid wave-transmission mechanism, the combination with the percussionrod and the working chamber for said rod, of a chamber which contains a'body of liquid serving as which, in conjunctionwithsaid rod, resonance depends, one portion of said rod being disposed in the latter chamber and having an area on which 'said'liquid acts to move the rod rearwardlfiiand a rearward portion of said rod passing hrough said working chamber an made o suc shoulder between it and the portion of the rod in front thereof, the operating liquid acting upon the area represented by' the said shoulder- 2. In a percussion tool for operation by compressional liquid wave-transmission mechanism, the combination with the eleinents claimed in claim 1, of a gland through 35 which the rear portion of the percussion rod passes to the atmosphere.

3.111 a percussion tool for operation by compressional liquid wave-transmission mechanism,the combinationwith the elements claimed in claim 1, of a relief valve for the body of liquid, this valve being set to open automatically at a predetermined pressure during the operation of the tool.

i. In a percussion tool for operation by compressional liquid wave-transmission mechanism, the combination with the elements claimed in claim 1, of a gland through which the rear portion of the percussion rod passes to the atmosphere and a relief valve for the body of liquid this valve being set to open automatically at a predetermined pressure,

during'the operation of the tool,

' 5-, In a percussion tool for operation by compressional liquid wave-transmission mechanism, the combination with the elements claimed in claim 1, of a conduit b etween the working chamber and the chamber smechanismfthe combination with the containing the body of liquidand an adjustable valve con rolling his onduit n. a P rcu ion. oo for op ration by c mpr ssio al liq d a m s i releinent claimed in claim 1., of a g nd hrough which the rea portion of the percuss n rod passes to he. atmosphe e, a conduit. between the Wo king, theat d the chamber tenthe resilient element on diameter as to provide a r taining the body of liquid and an adjustable valve controlling this conduit. 1 WlLLl AM RUSSELL DEGENHARDT.

ALLAN FRED de FRAINE.

.ROBERT. ALAN WIMBERLEY BICKNELL,

ARTHUR BICKNELL, Administrators for Robert Henry Bi'cknell, De-

ceased. 

